Outdoor Aerobiology^ 



By P. H. Gregory 



Head, Department of Plant Pathology 



Rothamsted Experimental Station 



Harpenden, England 



[With 2 plates] 



To THE sufferer from hay fever there "will be nothing novel in the 

 idea that outdoor air contains the pollen of many different kinds of 

 flowering plants. But the air also contains many other particles of 

 biological origin, such as the spores of cryptogams, fungi, bacteria, 

 and yeasts, and also protozoan cj'sts, some of which may also cause 

 allergies. Some species in all the major taxonomic groups of plants 

 have evolved means of introducing their spores into the turbulent 

 layers of the atmosphere [6].^ Other organisms, however, are 

 adapted to other dispersal routes, such as water or animal transport, 

 and their spores seldom get into the air. 



The systematic study of the microbiology of the atmosphere started 

 about a century ago, in the expectation of finding the source of epi- 

 demic diseases such as cholera and typhoid. It is now clear, however, 

 that outdoor air is not a serious source of human infection and it has 

 been acquitted of complicity in the worst human and animal diseases, 

 though recent American work shows that the agents of histoplasmosis 

 and other fungus diseases of man are windborne. Outdoor air also 

 conveys pollen, a major nuisance to hay-fever victims, and also in- 

 fective spores of many important crop pathogens, such as the rusts 

 and smuts of cereals. 



In effect, aerobiology began at the Observatoire Montsouris in Paris 

 with the work of the bacteriologist Pierre Miquel (1850-1922), who 

 elaborated techniques that enabled him, throughout the last quarter 

 of the 19th century, to analyze daily the microbial content of outdoor 

 air. However, the first to attempt consciously to develop aerobiology 

 as an individual branch of science was a plant pathologist, Fred C. 

 Meier (1893-1938). Unfortunately he was lost on a flight over the 

 Pacific after publishing no more than a few preliminary papers ; these 



1 Reprinted by permission from Endeavour, vol. 19, No. 76, October 1960. 

 * Numbers in bracliets indicate references at end of text. 



445 



